Fix border radius on composited children.

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h

 /*
  * Copyright (C) 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 357 matching lines @@
   LayoutBoxModelObject* layoutObject() const {
     return m_owningLayer.layoutObject();
   }
   PaintLayerCompositor* compositor() const {
     return m_owningLayer.compositor();
   }
 
   void updateInternalHierarchy();
   void updatePaintingPhases();
   bool updateClippingLayers(bool needsAncestorClip, bool needsDescendantClip);
+  bool updateClippingLayers(bool needsAncestorClip,
+                            bool needsAncestorClippingMask,
+                            bool needsDescendantClip);
   bool updateChildTransformLayer(bool needsChildTransformLayer);
   bool updateOverflowControlsLayers(bool needsHorizontalScrollbarLayer,
                                     bool needsVerticalScrollbarLayer,
                                     bool needsScrollCornerLayer,
                                     bool needsAncestorClip);
   bool updateForegroundLayer(bool needsForegroundLayer);
   bool updateBackgroundLayer(bool needsBackgroundLayer);
   bool updateMaskLayer(bool needsMaskLayer);
   void updateChildClippingMaskLayer(bool needsChildClippingMaskLayer);
   bool requiresHorizontalScrollbarLayer() const {
@@ skipping 73 matching lines @@
   // contains this squashed layer's clipping ancestor.  The clip rect is
   // returned in the coordinate space of the given squashed layer.  If there is
   // no such containing layer, returns the infinite rect.
   // FIXME: unify this code with the code that sets up m_ancestorClippingLayer.
   // They are doing very similar things.
   static IntRect localClipRectForSquashedLayer(
       const PaintLayer& referenceLayer,
       const GraphicsLayerPaintInfo&,
       const Vector<GraphicsLayerPaintInfo>& layers);
 
-  // Return true if |m_owningLayer|'s compositing ancestor is not a descendant
-  // (inclusive) of the clipping container for |m_owningLayer|.
-  bool owningLayerClippedByLayerNotAboveCompositedAncestor(
-      const PaintLayer* scrollParent);
+  // Return true in |owningLayerIsClipped| iff |m_owningLayer|'s compositing
+  // ancestor is not a descendant (inclusive) of the clipping container for
+  // |m_owningLayer|. Return true in |owningLayerIsMasked| iff
+  // |owningLayerIsClipped| is true and |m_owningLayer|'s compositing ancestor
+  // is not a descendant (inclusive) of a container that applies a mask for
+  // |m_owningLayer|.
+  void owningLayerClippedOrMaskedByLayerNotAboveCompositedAncestor(
+      const PaintLayer* scrollParent,
+      bool& owningLayerIsClipped,
+      bool& owningLayerIsMasked);

[Stephen Chennney, 2016/11/08 21:42:51]

Not sure if it's a good idea to set two things with the same method, but it
avoids computing all the clipping container info twice.

 
   const PaintLayer* scrollParent();
 
   // Clear the groupedMapping entry on the layer at the given index, only if
   // that layer does not appear earlier in the set of layers for this object.
   bool invalidateLayerIfNoPrecedingEntry(size_t);
 
   PaintLayer& m_owningLayer;
 
   // The hierarchy of layers that is maintained by the CompositedLayerMapping
@@ skipping 30 matching lines @@
   //  + B = m_ancestorClippingLayer [+]
   //     + m_graphicsLayer
   //        + ...
   //
   // In this case B is clipped by another layer that doesn't happen to be its
   // ancestor: A.  So we create an ancestor clipping layer for B, [+], which
   // ensures that B is clipped as if it had been A's descendant.
 
   // Only used if we are clipped by an ancestor which is not a stacking context.
   std::unique_ptr<GraphicsLayer> m_ancestorClippingLayer;
+
+  // Only used is there is an m_ancestorClippingLayer that also needs to apply
+  // a clipping mask (for CSS clips or border radius).
+  std::unique_ptr<GraphicsLayer> m_ancestorClippingMaskLayer;
+
   std::unique_ptr<GraphicsLayer> m_graphicsLayer;
 
   // Only used if we have clipping on a stacking context with compositing
   // children.
   std::unique_ptr<GraphicsLayer> m_childContainmentLayer;
 
   // Only used if we have perspective.
   std::unique_ptr<GraphicsLayer> m_childTransformLayer;
 
   // Only used if the layer is using composited scrolling.
@@ skipping 114 matching lines @@
   // Keep track of whether the background is painted onto the scrolling contents
   // layer for invalidations.
   unsigned m_backgroundPaintsOntoScrollingContentsLayer : 1;
 
   friend class CompositedLayerMappingTest;
 };
 
 }  // namespace blink
 
 #endif  // CompositedLayerMapping_h